Day 3: More tests..

src/main/kotlin/day3/Day3.kt

@@ -12,7 +12,7 @@ object Day3 {
             }
             .sumOf { it.number }
 
-    private fun readLines(file: String): List<String> =
+    fun readLines(file: String): List<String> =
         File(file)
             .readLines()
 
@@ -28,7 +28,7 @@ object Day3 {
                                     Part(
                                         number.toInt(),
                                         Coordinate(x, y),
-                                        Coordinate(x + number.length, y)
+                                        Coordinate(x + number.length - 1, y)
                                     )
                                 )
                             }

src/test/kotlin/day3/Day3Test.kt

@@ -2,6 +2,7 @@ package day3
 
 import org.junit.jupiter.api.Assertions.assertEquals
 import org.junit.jupiter.api.Test
+import kotlin.test.assertContentEquals
 
 class Day3Test {
 
@@ -9,4 +10,22 @@ class Day3Test {
     fun readParts() {
         assertEquals(4361, Day3.sumOfSelectedParts("src/test/resources/day3/input.txt"))
     }
+
+    @Test
+    fun testReadParts() {
+        assertContentEquals(
+            listOf(467, 114, 35, 633, 617, 58, 592, 755, 664, 598),
+            Day3.readParts(Day3.readLines("src/test/resources/day3/input.txt")).map(Part::number)
+        )
+    }
+
+    @Test
+    fun testOnly114And58DropOut() {
+        assertContentEquals(
+            listOf(467, 35, 633, 617, 592, 755, 664, 598),
+            Day3.readLines("src/test/resources/day3/input.txt").let { lines ->
+                Day3.readParts(lines).filter { part -> part.isSelected(lines) }.map(Part::number)
+            }
+        )
+    }
 }